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H Katagiri

Publications and source records attributed to H Katagiri.

At least 127 records · Page 7Linked to original sources
PubMed1992

Expression of glucose transporter isoforms with aging.

To elucidate the cellular mechanisms for impairment of glucose metabolism associated with aging, the facilitative glucose transporter protein and mRNA were studied in various tissues of young (7-week-old) and aged (20-month-old) rats. GLUT4 glucose transporter protein, a major glucose transporter isoform in the insulin-responsive tissues, was selectively decreased in the epididymal fat tissues of the aged rats compared with the young rats. This decrease is likely to be due to a decrease in protein synthesis rather than in protein stability, since GLUT4 mRNA per unit cellular total RNA was also decreased. GLUT4 mRNA in the skeletal muscle was rather increased in spite of the decreased level of GLUT4 protein in the aged rats, suggesting that the translational efficiency and/or stability of GLUT4 protein is decreased in the skeletal muscle of the aged rats compared with the young rats. In contrast to these alterations in GLUT4 expression, no apparent decrease in the GLUT1 protein amount was observed in the fat tissues, skeletal muscle and brain of the aged rats compared with the young rats. Thus, the tissue and isoform-specific alterations in glucose transporter expression are associated with aging and may contribute to impairment of glucose metabolism observed with aging.

Adipose Tissue↗
PubMed1992

Upregulation of GLUT2 mRNA by glucose, mannose, and fructose in isolated rat hepatocytes.

Previously, demonstrated that GLUT2 mRNA and protein are increased in liver of streptozocin-induced diabetic rats. To examine the mechanisms whereby GLUT2 mRNA is regulated, we cultured isolated hepatocytes in the absence and presence of various concentrations of glucose. Culture of hepatocytes in high glucose concentration (27.8 mM) for 20 h induced a 3.2-fold increase in GLUT2 mRNA levels compared with hepatocytes cultured without D-glucose. Interestingly, D-mannose and D-fructose could substitute for D-glucose to elevate the GLUT2 mRNA level, whereas 3-O-methyl-D-glucose, 2-deoxy-D-glucose, and sucrose, which were not metabolized or taken up by the cells, were without effect. Insulin had no significant effect on GLUT2 mRNA levels in hepatocytes in the presence or absence of D-glucose. Therefore, the regulation of the GLUT2 gene by D-glucose in hepatocytes is contrary to that reported for GLUT1 and GLUT4 genes, which are downregulated by D-glucose. These results also suggest that the elevated GLUT2 mRNA level observed in diabetic rat liver is due to the high blood glucose concentration rather than to insulin deficiency.

3-O-Methylglucose↗
PubMed1991

The role of N-glycosylation of GLUT1 for glucose transport activity.

To elucidate a functional role of N-glycosylation in glucose transporters, we introduced oligonucleotide-directed mutagenesis in GLUT1 cDNA to remove the possible site for N-linked glycosylation. The wild-type and the mutated GLUT1 cDNAs which induced a mutation of Asn at residue 45 to Asp, Tyr, or Gln were transfected and stably expressed into Chinese hamster ovary cells. The expressed wild-type and the mutated GLUT1 was demonstrated to be a broad band of a 45-60-kDa form and a sharp band of a 38-kDa form on Western blot analysis, respectively, indicating no glycosylation in the mutated GLUT1. Although the cell surface labeling of the glucose transporters demonstrated the presence of the glycosylation-defective glucose transporters on the cells surface, photoaffinity labeling of glycosylation-defective GLUT1 with [3H] cytochalasin B and a photoreactive mannose derivative, [3H]2-N-4-(1-azi-2,2,2,trifluoroethyl)benzoyl-1,3-bis(D-mannos+ ++-4-yloxy)-2- propylamine in the membranes was observed to be 40-70 and 15-30% of that of the wild-type GLUT1, respectively. The kinetic study of 2-deoxyglucose uptake revealed that the glycosylation-defective GLUT1 had a 2-2.5-fold greater Km value for 2-deoxyglucose uptake compared with the wild-type GLUT1. These observations strongly suggest that 1) N-glycosylation of GLUT1 glucose transporter is only on Asn 45 and 2) N-glycosylation plays an important role in maintaining a structure of glucose transporter with high affinity for glucose, thus, with high transport activity.

Affinity Labels↗
PubMed1991

Expression of the GLUT1 glucose transporter increases thymidine uptake in Chinese hamster ovary cells at low glucose concentrations.

An increase in expression of the GLUT1 glucose transporter gene has been observed to be associated with an increase in glucose transport activity upon oncogenic transformation of the cells. Increased expression of this glucose transporter isoform has been also observed in fetal tissues. To investigate the consequences of this phenomenon on cellular metabolism and cell growth, an expression vector containing the GLUT1 glucose transporter complementary DNA was transfected into Chinese hamster ovary cells. Overexpression of this glucose transporter isoform resulted in an increase in not only glucose uptake and utilization but also thymidine uptake when cells were exposed to glucose-deficient conditions. This increase in glucose metabolism and DNA synthesis may play an important role on the growth and/or survival of cancer cells and fetal tissues.

3-O-Methylglucose↗
PubMed1991

The glucose transport activity of GLUT1 is markedly decreased by substitution of a single amino acid with a different charge at residue 415.

GLUT1 glucose transporter cDNA was modified to introduce a single amino acid substitution of aspartic acid for asparagine 415, which is conserved among all facilitative glucose transporter isoforms. Although a significant amount of the mutated transporter was expressed into plasma membranes of Chinese hamster ovary cells by transfection with expression vector, almost no increase in glucose transport activity was observed. Analysis of glucose uptake with Lineweaver-Burk plot depicts that the mutation induced a marked decrease (more than 5-fold) in turnover number and a slight increase (1.5-fold) in Km compared with the wild-type GLUT1. Results obtained with cytochalasin B and ethylidene glucose suggested that the inner but not outer glucose binding site was modulated. These results suggest that asparagine 415 is located close to the inner glucose binding site and the putative inner gate of GLUT1 glucose transporter and that an ionic charge in this domain might play an important role in the rate of conformational change between an inward-facing form and an outward-facing form of glucose transporter.

Animals↗
PubMed1991

Substitution of leucine for tryptophan 412 does not abolish cytochalasin B labeling but markedly decreases the intrinsic activity of GLUT1 glucose transporter.

GLUT1 glucose transporter cDNA was modified to introduce a single amino acid substitution of leucine for tryptophan 412, a putative cytochalasin B photo-affinity labeling site. Although the mutated transporter was expressed into plasma membranes of Chinese hamster ovary cells, glucose transport activity of the mutated transporter was observed to be only 15-30% of that of the wild-type GLUT1 when glucose transport activity was assessed by 2-deoxyglucose uptake at 0.1-10 mM concentrations. Analysis of glucose uptake kinetics depict that a mutation induced a 3-fold decrease in turnover number and a 2.5-fold increase in Km compared with the wild-type GLUT1. Importantly, cytochalasin B labeling was not abolished but decreased by 40%, and cytochalasin B binding was also decreased. In addition, the results obtained with side-specific glucose analogs suggested that the outer glucose binding site of the mutant appeared intact but the inner binding site was modulated. These results indicate 1) tryptophan 412 is not a cytochalasin B labeling site(s), although this residue is located in or close to the inner glucose binding site of the GLUT1 glucose transporter, 2) substitution of leucine for tryptophan 412 decreases the intrinsic activity of GLUT1 glucose transporter, which is definable as the turnover number/Km, to approximately 15% of that of the wild-type.

Affinity Labels↗
PubMed1991

Altered expression of glucose transporter isoforms with aging in rats--selective decrease in GluT4 in the fat tissue and skeletal muscle.

To elucidate the cellular mechanisms of glucose intolerance associated with aging, both the protein and mRNA levels of glucose transporter isoforms were studied in the various tissues of young (7-week-old) and aged (20-month-old) rats. GluT4 (adipose/muscle-type glucose transporter) protein, which is specifically expressed in insulin-responsive tissues, was selectively decreased per milligram of cellular membrane protein in both the epididymal fat tissues and the gastrocnemius muscle of the aged rats compared with the young rats. When the changes in total cellular membranes per gram of tissue are taken into account, a further decrease in GluT4 protein per gram of tissue was observed in the tissues of the aged rats compared with the young rats. The decreased amount of GluT4 protein in the fat tissues of the aged rats is probably due to the decreased protein synthesis rather than the stability, since GluT4 mRNA/micrograms of cellular total RNA was also decreased. In contrast, GluT4 mRNA in the gastrocnemius muscle was rather increased and a ratio of GluT4 protein/GluT4 mRNA was decreased by 70% in the aged rats, suggesting that the translational efficiency and/or stability of GluT4 protein is decreased in the skeletal muscle of the aged rats compared with the young rats. GluT2 (liver-type glucose transporter) protein and mRNA in the liver were also decreased in the aged rats, while no apparent decrease in GluT1 (HepG2/brain-type glucose transporter) protein/mg of cellular membrane protein was observed in the skeletal muscle and fat tissues of the aged rats compared with the young rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1991

Impact of supersonic versus propeller wind data on dispersion estimates for nuclear plants.

Statistical analyses and comparisons of the wind data obtained by the propeller and supersonic anemometers at the Japan Atomic Energy Research Institute (JAERI) were performed. For wind speeds less than 1 ms-1, the propeller readings are inaccurate and are generally 0.5 ms-1 less than the supersonic readings. Thus, the number of calms recorded differs. These differences affect the sum of the inverse of wind speed, frequency distribution of wind direction, and the annual percentage frequency distribution of stability categories. The resultant average air concentrations and ground-level gamma exposure rates due to the normal operational releases from a nuclear plant are overestimated when calculated using the propeller wind data.

Air Pollutants, Radioactive↗
PubMed1991

Peptide-based radioimmunoassay specific for GLUT1 glucose transporter.

A radioimmunoassay for the GLUT1 glucose transporter was developed with a synthesized peptide based on the sequence of the cDNA for GLUT1. A peptide corresponding to the COOH-terminal domain of the GLUT1 glucose transporter (Thr-Pro-Glu-Glu-Leu-Phe-His-Pro-Leu-Gly-Ala-Asp-Ser-Gln-Val) was synthesized and conjugated to keyhole limpet hemocyanin through the NH2-terminal of the peptide. An antibody was raised against this complex and affinity purified with the immobilized peptide. A second peptide, with tyrosine residue added to the NH2-terminal of the above peptide, was synthesized and used as a standard and iodinated for preparation of the radioactive ligand. The assay is highly reproducible, sensitive, and specific for the COOH-terminal domain of the GLUT1 glucose transporter. It has no cross-reactivity with the other glucose-transporter isoforms GLUT2 and GLUT4. Furthermore, the results obtained with this radioimmunoassay on the number of glucose transporters in human erythrocytes were in good agreement with previous studies based on cytochalasin B binding, suggesting that this radioimmunoassay is able to quantify the number of glucose transporters. The assay is completed within 4 h and can be used for simultaneous measurement of GLUT1 in many samples. In addition, it can be applied to the measurement of GLUT1 in several types of tissue.

Amino Acid Sequence↗
PubMed1991

[Study on cases of D dimer values were dissociated from FDP-E].

Determination of FDP D-dimer (D-dimer) has been recently developed for the diagnosis of thrombotic diseases with secondary fibrinolysis. We have studied the correlation between D-dimer and FDP-E concentrations in plasma from 282 patients with 630 samples. A linear correlation (r = 0.9269) was observed between the values of FDP-E and D-dimer. However, 13 out of 282 cases revealed an apparent dissociation of D-dimer concentrations from FDP-E values. Among them, 4 of these 13 cases (Group A) have shown to possess higher level of D-dimer when compared with the expected values from FDP-E, while 9 of 13 cases (Group B) revealed lower levels of D-dimer than that expected from FDP-E. All of Group A patients have been diagnosed as disseminated intravascular coagulation (DIC). On the other hand, in Group B patients, 6 of 9 were shown to have a widespread metastasis of cancer and 2 of them were under treatment with urokinase. To study whether Group B patients were under hypercoagulable or hyper-fibrinolytic state, we have examined ratios of AT III/alpha 2 PI and PIC/TAT in these cases. It has been shown that 4 of 9 patients in Group B have higher ratios of both AT III/alpha 2 PI and PIC/TAT if compared with other patients than Group B. This suggests that patients in Group B have been under hyper-fibrinolytic states.

Adult↗
PubMed1990

C-terminal truncated glucose transporter is locked into an inward-facing form without transport activity.

The facilitated glucose transporters comprise a structurally related family of proteins predicted to have 12 membrane-spanning domains, with the amino terminus, a relatively large middle loop and the carboxy-terminus all oriented towards the cytoplasm. An alternating conformation model has been proposed to explain the mechanism of facilitated glucose transport. To understand the structure-function relationships, especially the role of the intracellular C-terminal domain, we have modified the rabbit equivalent of the erythroid-type transporter, GLUT1 (ref. 18), using complementary DNA to code for a deletion mutant that lacks most (37 out of 42 amino acids) of the intracellular C-terminal domain. This deletion mutant is expressed at the cell surface of Chinese hamster ovary (CHO) cells, but is functionally inactive, probably because it has lost its capacity to alternate in conformation and so is locked into an inward-facing form.

Animals↗
PubMed1990

DNA analysis of periampullary cancers.

The nuclear DNA content in 71 cases of periampullary cancer (27, cancer of the head of the pancreas (Ph); 24, cancer of the ampulla of Vater (A); and 20, cancer of the inferior common bile duct (Bi] was measured cytofluorometrically using the archival paraffin-embedded specimens of the primary lesions. They were analyzed in relation to prognosis, tumor size, histological differentiation, lymph node metastasis, lymphatic invasion, venous invasion, perineural invasion, and growth pattern. The results show that "Ph" has more unfavorable prognosis compared with the other two and it has more DNA content under the same conditions such as tumor from 2.1 to 4 cm in its greatest dimension, well differentiated adenocarcinoma, with or without lymph node metastasis, with or without venous invasion, with lymphatic invasion, with perineural invasion, and in the intermediate growth pattern between expansive and infiltrative. In conclusion, this study demonstrates a close correlation between the DNA content and prognosis and the significant clinical value of DNA analysis for predicting the prognosis in patients of periampullary cancer.

Adenocarcinoma↗
PubMed1987

Initial phase II clinical studies on midaglizole (DG-5128). A new hypoglycemic agent.

Midaglizole (DG-5128), 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-phenylethyl]pyridine dihydrochloride sesquihydrate, is a new type of oral antidiabetic agent that has an alpha 2-adrenoceptor-antagonizing effect. As previously reported, midaglizole reduces plasma glucose, mainly by stimulation of insulin secretion, and inhibits epinephrine-induced platelet aggregation in normal human subjects. In this study, the clinical safety and efficacy of short-term administration of midaglizole were evaluated in 47 patients with non-insulin-dependent diabetes mellitus (NIDDM). After an observation period on diet or sulfonylurea treatment (1 patient was on insulin), patients received 150-250 mg 3 times a day of midaglizole for 2-4 wk, (some patients continued treatment for greater than 4 wk). In 20 of the patients first treated with diet and then switched to midaglizole treatment, fasting plasma glucose (FPG) decreased significantly from 187 +/- 10 mg/dl (mean +/- SE) to 147 +/- 13 mg/dl (P less than .05) and 120 +/- 6 mg/dl (P less than .01) 2 and 4 wk, respectively, after administration of midaglizole. Glycosylated hemoglobin (HbA1) also decreased from 12.0 +/- 0.7 to 11.3 +/- 1.1 and 10.7 +/- 0.6% after 2 and 4 wk, respectively. In 23 of the patients whose treatment was changed from sulfonylureas to midaglizole, FPG, and HbA1 levels were maintained at the same values obtained before administration of midaglizole. In patients treated with midaglizole for greater than 12 wk, FPG and HbA1 were kept at the lowered levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

Complete nucleotide sequence of mini-Rts1 and its copy mutant.

The nucleotide sequence of the whole mini-Rts1 genome consisting of 1,855 base pairs was determined. In addition to the cluster of five 24-base-pair direct repeats previously detected (Y. Kamio and Y. Terawaki, J. Bacteriol. 155:1185-1191, 1983), another cluster of three 21-base-pair direct repeats was found. All eight repeats were located in one direction and contained a consensus sequence TTCCCCPyPyPuPuCACACACC. Between the two clusters, a large open reading frame that could encode a 32,980-dalton polypeptide consisting of 288 amino acids was assigned. The molecular size predicted from the amino acid composition was close to the value of a unique mini-Rts1 product, the RepA protein, newly determined in minicells. A copy mutant of mini-Rts1 obtained in vitro by hydroxylamine treatment contained two-base-pair substitutions, one of which was located in the RepA protein coding region, and the other was close to the region where the oriC homologous sequences exist.

Ampicillin↗